An electric arc formed between a pair of conductors that are separated by an otherwise insulating gas may be designed to provide light, heat, sound, or radio frequency signals. By providing heat, the arc may be used to ignite the gas, for example for producing light, heat, or propulsion. In other applications for an electric arc, the arc may be designed to complete a circuit for current to flow through the arc and through a load. A circuit that causes an arc to form and thereafter supplies a current through the load is a drive circuit, as opposed to merely an igniter circuit, in part because it impresses across the conductors a voltage high enough to cause ionization of the gas and then provides a current through the arc and through the load. Prior to ionization, the insulating effect of the gas prevents current from flowing through the load. After ionization, the arc offers little resistance to current flow. An arc may be extinguished by reducing current flow through the arc to less than a current sufficient to maintain the arc or by increasing the insulating effect between the conductors (e.g., further separating the conductors, introducing matter between the electrodes of greater insulating effect, or removing ionized matter). With appropriate control circuits in the apparatus, the arc may perform a function of a switch to enable or disable current flow through the load.
After ionization, while the apparatus provides the current through the load, the load may change. Accordingly, the current provided to the load is somewhat non-uniform over a series of pulses intended to be uniform from one load to another or from one apparatus to another of a common type.
A conventional driver for a load that is isolated in the absence of an arc generally provides a fixed and relatively large amount of energy to assure ionization. There remains a need for an apparatus and methods performed by an apparatus that supplies an efficient amount of energy for ionization. There is a further need for an apparatus and methods performed by an apparatus that supplies an efficient amount of energy for ionization that may vary to meet changes from time to time in the insulating effect between the conductors. For example, the relatively large amount of energy expended for an ionization in a conventional igniter may be based on a theoretical maximum distance between the conductors. In other applications of igniters and drivers, the distance between the conductors may vary greatly. Using a fixed maximum amount of energy for every ionization can lead only to inefficient waste of energy for some ionization events.
It may be desirable to use as little energy as possible to overcome the insulating effect of the separation between the conductors, for example, so that a limited source of energy is conserved for completing the purposes of the current through the load.
After establishing a circuit through the load, it may be desirable in some applications to increase uniformity of pulses experienced by a load, for example, to provide a more accurate record of current delivered, to use minimum energy to provide a desired result, and to conserve energy expended by the apparatus as a whole. Conventional electronic weapons provide a stimulus signal as a series of pulses to a load. An amount of charge delivered by each pulse of the stimulus signal varies within manufacturing tolerances of the weapon and varies for a wide variety of loads that may be presented to the weapon. The load may change during stimulation. Accordingly, stimulus to the load is somewhat non-uniform over a series of pulses intended to be uniform from one load to another or from one weapon to another of a common type. Unless energy is conserved, the period of time an electrical weapon is available for use cannot be extended. Battery powered applications are among those applications having a limited source of energy.
Implementations according to various aspects of the present invention solve the problems discussed above and other problems, and provide the benefits discussed above and other benefits as will be apparent to a skilled artisan in light of the disclosure of invention made herein.